Power supply control apparatus and method of using the same

Abstract

A power supply control apparatus and method are provided. The apparatus includes a controller outputting a first pulse width modulation (PWM) signal for supplying an electric power and a second PWM signal to be compared to the first PWM signal, a first PWM signal input unit converting the second PWM signal to a direct current (DC) signal, a second PWM signal input unit receiving the converted second PWM signal, a comparator comparing the first PWM signal and the converted second PWM signal, a switching unit generating a waveform having a voltage according to the comparison result of the comparator, a transformer transforming the voltage of the generated pulse waveform according to the switching result of the switching unit and a rectifier and voltage divider for rectifying and voltage-dividing the transforming result of the transformer, wherein the controller adjusts the second PWM signal by receiving the rectifying and voltage-dividing result of the rectifier & voltage divider.

1. A power supply control apparatus comprising:
 a controller for outputting a first pulse width modulation (PWM) signal supplying alternating current (AC) power and a second PWM signal; 
 a first PWM signal input unit for converting the second PWM signal to a direct current (DC) signal; 
 a comparator for comparing the first PWM signal and the converted second PWM signal; 
 a transformer for producing an output voltage being an alternating current (AC) signal according to the comparison of the first PWM signal and the converted second PWM signal; and 
 a rectifier and voltage divider coupled to the transformer for rectifying and voltage-dividing the output voltage of the transformer, 
 wherein the output voltage of the transformer is supplied to a load, and the rectifying and voltage-dividing result is fed back to the controller, 
 wherein the controller adjusts the second PWM signal according to the fed back rectifying and voltage-dividing result in order to reduce a fluctuation of the output voltage of the transformer due to impedance fluctuation of the load. 
 
     
     
       2. The power supply control apparatus of  claim 1 , wherein the controller comprises an analog-to-digital converter (ADC) for receiving the rectifying and voltage-dividing result of the rectifier and voltage divider. 
     
     
       3. The power supply control apparatus of  claim 1 , wherein the controller adjusts a duty ratio of the second PWM signal to high if the controller determines that the output voltage of the transformer is lower than a reference value, and adjusts the duty ratio of the second PWM signal to low if the controller determines that the output voltage of the transformer is higher than the reference value. 
     
     
       4. The power supply control apparatus of  claim 2 , wherein the controller determines that the output voltage of the transformer is lower or higher than a reference value by referring to the rectifying and voltage dividing result of the rectifier and voltage divider. 
     
     
       5. The power supply control apparatus of  claim 1 , wherein the first PWM signal input unit comprises a resistor and a capacitor to convert the second PWM signal into a DC signal. 
     
     
       6. The power supply control apparatus of  claim 1 , further comprising a second PWM signal input unit for receiving the converted second PWM signal, wherein the second PWM signal input unit comprises at least two resistors to voltage-divide the second PWM signal. 
     
     
       7. The power supply control apparatus of  claim 1  further comprising a switching unit for generating a waveform having a voltage according to the comparison result of the comparator, wherein the switching unit comprises at least two transistors and at least two resistors to generate the pulse waveform having a voltage, and wherein the transformer transforms the voltage of the generated pulse waveform according to the switching result of the switching unit. 
     
     
       8. The power supply control apparatus of  claim 1 , wherein the rectifier and voltage divider comprises at least one diode, one capacitor, and one resistor to rectify and voltage-divide a positive (+) voltage corresponding to the transforming result of the transformer. 
     
     
       9. The power supply control apparatus of  claim 1 , wherein the rectifier and voltage divider comprises at least one diode, one capacitor, and one resistor to rectify and voltage-divide a negative (−) voltage corresponding to the transforming result of the transformer. 
     
     
       10. The power supply control apparatus of  claim 9 , further comprising a voltage applying unit for applying a voltage to the rectifier and voltage divider to input the rectified and voltage-divided negative (−) voltage to the controller. 
     
     
       11. The power supply control apparatus of  claim 10 , wherein the voltage has a value at least greater than the absolute value of the rectified and voltage-divided negative (−) voltage. 
     
     
       12. A power supply control method comprising:
 outputting by a controller a first pulse width modulation (PWM) signal supplying alternating current (AC) power and a second PWM signal; 
 converting the second PWM signal to a direct current (DC) signal; 
 comparing the first PWM signal to the converted second PWM signal to generate a comparison result; 
 transforming by a transformer a voltage of the generated waveform to produce an output voltage being an alternating current (AC) signal according to the comparison result; 
 rectifying and voltage-dividing the output voltage of the transformer to generate a rectifying and voltage-dividing result; and 
 adjusting by the controller the second PWM signal according to the rectifying and voltage-dividing result, 
 wherein the output voltage of the transformer is supplied to a load, and the rectifying and voltage-dividing result is fed back to the controller, and 
 wherein the controller adjusts the second PWM signal according to the rectifying and voltage-dividing result in order to reduce a fluctuation of the output voltage of the transformer due to impedance fluctuation of the load. 
 
     
     
       13. The power supply control method of  claim 12  further comprising generating a pulse waveform having a voltage according to the comparison result, and
 wherein the transforming comprises transforming the voltage of the generated waveform. 
 
     
     
       14. The power supply control method of  claim 12 , wherein the rectifying and voltage-dividing of the transforming result comprises rectifying and voltage-dividing at least one of a positive (+) and a negative (−) voltage corresponding to the transforming result. 
     
     
       15. The power supply control method of  claim 14 , wherein a voltage is applied to the rectified and voltage-divided negative (−) voltage. 
     
     
       16. The power supply control method of  claim 15 , wherein the voltage has a value at least greater than the absolute value of the rectified and voltage-divided negative (−) voltage. 
     
     
       17. The power supply control method of  claim 12 , wherein the adjusting of the second PWM signal comprises adjusting a duty ratio of the second PWM signal to high if it is determined that the transformed voltage is lower than a reference value by referring to the rectifying and voltage-dividing result, and adjusting the duty ratio of the second PWM signal to low if it is determined that the transformed voltage is higher than the reference value by referring to the rectifying and voltage-dividing result. 
     
     
       18. A computer readable recording medium having stored thereon instructions for executing a power supply control method, the instructions comprising:
 a first set of instructions for outputting a first pulse width modulation (PWM) signal supplying alternating current (AC) power and a second PWM signal; 
 a second set of instructions for converting the second PWM signal to a direct current (DC) signal; 
 a third set of instructions for comparing the first PWM signal to the converted second PWM signal; 
 a fourth set of instructions for producing an output voltage being an alternating current (AC) according to the comparison of the first PWM signal and the converted second PWM signal; 
 a fifth set of instructions for rectifying and voltage-dividing the output voltage to generate a rectifying and voltage-dividing result; and 
 a sixth set of instructions for adjusting the second PWM signal according to the rectifying and voltage-dividing result. 
 
     
     
       19. The power supply apparatus of  claim 6 , wherein the generated waveform is a pulse waveform. 
     
     
       20. The power control apparatus of  claim 1 , wherein the load comprises a developing unit of a printer. 
     
     
       21. A printer comprising:
 a load; 
 a power supply unit including (1) a controller that generates a first pulse width modulation (PWM) signal and a second PWM signal, (2) a conversion unit that converts the second PWM signal to a direct current (DC) signal, (3) a comparator that compares the first PWM signal and the converted second PWM signal, (4) a switching unit that generates a waveform having a voltage according to a comparison of the first PWM signal and the converted second PMW signal, and (5) a transformer that produces an output voltage according to the waveform generated by the switching unit; and 
 a rectifier and voltage divider coupled to the transformer for rectifying and voltage-dividing the output voltage of the transformer to output a rectifying and voltage-dividing result, 
 wherein the output voltage of the transformer is supplied to the load, and the rectifying and voltage-dividing result is fed back to the controller, 
 wherein the controller adjusts the second PWM signal according to the fed back rectifying and voltage-dividing result in order to reduce a fluctuation of the output voltage of the transformer due to impedance fluctuation of the load. 
 
     
     
       22. The printer of  claim 20 , wherein the load comprises a developing unit.